1. Field of the Invention
The invention relates to a low-induction anode-cathode R-C circuit for a gate-turn-off power thyristor.
2. Discussion of Background
State of the art low-inductance anode-cathode R-C circuits for a gate-turn-off power thyristor are described in IEEE Transactions on Industry Applications, Vol. IA-19, 3(1983) pages 343-344. In this paper, two gate-turn-off thyristors, so-called GTO thyristors, which are designed for 2500 V/1000 A, are connected in parallel via current balancing chokes, for vehicle drives with a power of 600 kvA. A diode is connected in antiparallel and a turn-off un-loading circuit consisting of an R-C circuit diode in parallel with a resistor and a capacitor connected in series therewith is connected in parallel with each GTO thyristor. When the thyristor is turned off, a steep voltage rise with a peak or a pulse point is caused to occur at it, mainly due to stray inductances of the components and lines of the turn-off unloading circuit, which can lead to the thyristor being destroyed. To reduce the inductance of the turn-off unloading circuit, low-inductance capacitors and diodes and short lines, particularly flexible coaxial lines, are used.